We shall characterize the human granulocyte oxidase (O2 negative and H2O2-producing) system as completely as possible - from the soluble cytoplasmic enzyme that links to quinones, to the final membrane-linked components that are apparently "ecto" in nature. This involves purification of the soluble component, establishment of its nature, function and mode of regulation; identification of the membrane-bound electron acceptor and of the final link to oxygen (a cytochrome b type enzyme?). We shall continue our study of tumor killing by activated macrophages in a system in which macrophages are sequentially exposed to Listeria, Listeria-sensitized T-lymphocytes, and 51Cr-labeled target cells. The macrophage monolayers are washed between exposures. We shall attempt to define the precise cells involved in the killing, and locale (membrane?) of the superoxide-peroxide producing enzyme by E.M.-cytochemical studies. Effects of MIF and other lymphokines on the macrophage metabolism will be compared. Aldehyde oxidase (O2-producing) in guinea pig granulocytes will be purified, characterized, and localized. The last may require development of a new cytochemical detection system. Metabolic differences between adherent (monolayer) cells, and the same cells in suspension will be further explored. More definitive data on the potential role of the myeloperoxidase-H2O2 system in cleaving proteins and deaminating and decarboxylating amino acids to aldehydes will be obtained in granulocytes.